Fix playback reporting to media servers

[timusus]

This commit resolves issue #96 by adding playback reporting functionality for remote media servers. The implementation follows the existing architecture patterns and integrates seamlessly with the playback system.

Changes:

1. Created PlaybackReportingService for each provider:

   • Jellyfin: POST /Sessions/Playing, /Playing/Progress, /Playing/Stopped
   • Emby: Same endpoints as Jellyfin (compatible API)
   • Plex: GET /:/timeline for state updates, /:/scrobble for completion

2. Added PlaybackInfo data classes for each provider:

   • Jellyfin/Emby: PlaybackStartInfo, PlaybackProgressInfo, PlaybackStopInfo
   • Plex: Uses query parameters with PlaybackState enum

3. Updated DI modules to provide PlaybackReportingService instances:

   • JellyfinMediaProviderModule
   • EmbyMediaProviderModule
   • PlexMediaProviderModule

4. Created PlaybackReporter coordinator class:

   • Implements PlaybackWatcherCallback to listen for playback events
   • Routes reporting to appropriate service based on Song.mediaProvider
   • Manages session IDs and progress reporting intervals (10s)
   • Handles playback start, progress updates, pause/resume, and stop
   • Only reports for remote providers (not local files)

5. Created PlaybackReporterInitializer:

   • Registers PlaybackReporter with PlaybackWatcher on app startup
   • Integrated via AppModuleBinds using Hilt's multibinding

Architecture:

• Follows Observer pattern (PlaybackWatcherCallback)
• Uses Strategy pattern for provider-specific implementations
• Dependency injection via Hilt for all components
• Coroutine-based async operations
• Proper error handling with Timber logging

Benefits:

• Jellyfin/Emby/Plex servers now receive "now playing" updates
• Server dashboards show active playback sessions
• Playback history is tracked on the server side
• Play counts and progress are synced to servers
• No changes required to existing playback logic

Fixes #96